Oh, oh...here we go again. WAIT, I just said that on another thread.
UDT is the standard. SUDT is useful in cold weather areas but still not absolutely necessary. Some dealers don't even stock it from what has been said in other posts.
SUDT in smaller tractors, like my BX2200 can smooth out the HST and reduce noise.
But it is your choice. Question: Why are you considering SUDT? That may help others in their response.